Die assembly



July 10, 1951 'r. 5. SEE 2,559,679

DIE ASSEMBLY Filed Feb. 10, 1948 Patented July 10, 1951 DIE ASSEMBLY Theodore S. See, Hammond, Ind., assignor to La Salle Steel Company, Chicago, 111., a corporation of Delaware Application February 10, 1948, Serial No. 7,374

13 Claims. 1

This invention relates to improvements in the construction of dies for use in the cold drawing of metal stock such as bars, rods, and other metal articles and more particularly to the design and construction of dies of this character which, among other purposes, are adapted for use in practicing the method disclosed in application Serial No. 773,230 filed September 10, 1947, and now forfeited, in the names of Sims and Landis, and assigned to the assignee of the present application.

In the co-pending application referred to, there is disclosed a new and improved method of cold reducing metal articles wherein cracking of the articles, during or after the reduction, is eliminated. Furthermore, the method disclosed therein contemplates the employment of heavier than normal drafts combined with freedom from cracking. Briefly, the method consists in entirely or substantially eliminating cracking by drawing the metal through a high reduction die and then through a low reduction die which ar positioned in tandem and spaced within a critical distance of one another, as described more fully in the afore-mentioned application, the subject matter of which, in order to avoid repetition, is incorporated herein by way of reference.

With the foregoing desideratum in mind, an object of the present invention consists in the provision of a new and improved tandem die assembly of durable character which is eflicient in operation and which is constructed and arranged in such a manner as to enable the reducing operation to produce articles that are straight, accurate in dimensions and free of cracks.

A feature of the invention which contributes to the accomplishment of the recited object consists in mounting a plurality of dies, which together form a tandem die assembly, in a housing in such a manner that the dies may be properly aligned with one another and with the longitudinal axis of the metal article being reduced.

Another feature of the invention resides in the contour of the working or bearing surfaces of the dies, the contour being adapted to control or direct the internal stresses and to reduce them to a A further feature of the invention consists in the provision of a plurality of dies, which together form a tandem die assembly, the working or bearing surfaces of the dies spaced apart a critical distance in order to conform the deployment of the dies to varying characteristics or conditions that are encountered in operation and use, such as, for instance, the degree of reduction 2 7 that is taken, the chemistry of th steel being Operated upon, the size of the article being reduced, and the like.

An additional feature resides in the provision of a die assembly of the character described which may be easily installed in or removed from the housing of a draw bench to permit interchangeability'of dies in order to accommodate articles of various shapes and sizes.

Other objects and features of the invention will become apparent from a reading of the following specifications in the light of the accompanying drawings, in which:

Figure 1 is a view in front elevation of a die assembly constructed in accordance with the present invention;

Figure 2 is a vertical view, in section, of the assembly shown in Figure 1, and

Figure 3 is an enlarged, fragmentary view showing the contour of the working or bearing surface of the reducing die.

As more fully described in the vco-pending application referred to above, it has been discovered that metal articles such as rods and bars may be cold reduced without cracking by (1) passing the articles through a reduction means of sufficiently high reduction to raise critically high stresses in the articles (stresses sufliciently high to crack the articles) and (2) then passing the articles through a reduction means of sufficiently low reduction to reform the stresses to those having non-critical (non-cracking) values. The high reduction means and the low reduction means, as disclosed herein, comprise a reducing die adapted to subject the metal to a heavy or abnormal draft and a second die adapted to subject the metal to a light draft to relieve residual stresses resulting from the heavy or abnormal draft. In order to practice the inethod satisfactorily the two reducing dies, which together comprise the tandem die assembly, must be positioned within a critical distance of one another, by which term is meant that distance within which no cracking will occur for the particular bar being drawn.

Turning now to the drawings, the reference numeral 10 indicates a die housing .which may be that of an ordinary draw bench of conventional pattern. It has been deemed unnecessary to show the conventional structure of a draw bench since it does not constitute a part of the invention disclosed herein and is old and well known in the art. 7

The draw bench is provided with a housing l0 having an opening therein, the wall of which is spherical in contour, as shown at the point indicated by the reference numeral 12, to receive the die assembly which is indicated generally by the letter A.

The die assembly comprises, generally speaking, a heavy reduction die l4 and a, light reduction die l6 each being mounted in suitable supporting members. As shown in Figure 2, the light reduction die l6, made of hardened metal suitably designed for the purpose, is firmly positioned within a stock or matrix 18 which is, in turn, mounted within an annular recess 20 formed in a die ring or frame 22. A gland or guide 24 is also carried within the die ring 22 and is provided with a flange 26 adapted to fit snugly within a corresponding annular recess formed in the die ring.

The guide or guard die 24, which forms the exit portion of the assembly, comprises an important part of the present invention. It may be employed with or without the reduction die I6. The main function that it serves is to assure the production or drawing of straight bars. Accordingly, this guide die, which is preferably made of heat-treated, high-grade, tool steel, may be regarded as a straightening die or as means that will assure the production of straight bars. This is particularly true with respect to the ends of bars being pushed through the assembly. In the absence of the guide die 24 there might be a tendency on the part of the end of the bar, after passing through the die l4 (and the die 16 if the latter is employed) to emerge in a crooked condition and this tendency is eliminated through the provision of the guide die 24 which straightens the end of the bar and gives assurance to the fact that the drawn bar will be straight throughout its entire length. The inner diameter of the die 24 corresponds approximately to the outer diameter of the bar.

The die M which is adapted initially to impart a high or abnormal reduction to the metal is mounted in a stock or matrix 30 which is ring shaped with its outer surface provided with a slight taper, as indicated at the point 32, to provide wedging engagement with the correspondingly tapered wall of a die ring or frame 34.

In assembling the structure, the light reduction die I 6' and its supporting matrix 18 are fitted within the die ring or frame 22 and these parts are inserted into the spherically shaped opening in the housing 10. Thereafter the heavy reduction die and its supporting matrix 30 are fitted within the die ring or frame 34 and these parts are likewise inserted into the spherically shaped opening in the housing Hi to complete the assembly. To hold the latter in place with the die l4 improperly adjusted axial relation, a plurality of circumferentially spaced clamping member 36 arranged to engage the rear surface of the die ring 34 and carried by the housing by means of bolts 38, may be provided. It will be appreciated that by virtue of the fact that both the die assembly and the opening or socket which receives the assembly are spherically formed, a ball and socket bearing is afforded which permits the dies to be easily adjusted and aligned with respect to the housing l and the longitudinal axis of the metal articles being reduced on the draw bench.

In order to enable the light and heavy reduction die to be properly positioned with respect to one another, a plurality of axially adjustable members or aligning pins 40 having screw threaded engagement with the die rin or frame 34 may be provided. It will be understood that the contour of the spherical wall 12 formed in the housing ID, on the one hand. and the outer contours of the die rings or frames 22 and 34. on the other hand, will control the degree or amount of separation between the said die rings or frames 22 and 34. However, the pins 40 may be employed for the purpose of effecting relative angular adjustments of the rings 22 and 34 in order properly to align the reduction dies I4 and It with respect to one another and bring their axes into alignment with one another.

In order to lubricate the metal during the reducing operation, oil, under pressure, may be supplied through a passageway 42 formed in the housing Ill.

Turning now to Figure 3, which shows one form which the contour of the workin or bearing surface of the heavy reduction die 14 may take, it will be observed that the surface comprises three sections or areas which may be designated as an entrant area 50, an intermediate area 52 and a cylindrical, drawing area 54. As illustrated herein, the entrant area is of an angular or tapering design with the angle between the surface of this area and the longitudinal axis of the die being shown as comprising 7 degrees. This angle, which is sometimes referred to as a half-angle, owing to the fact that it represents only one-half of the full entrant angle of the die, will vary depending upon the nature or size of the material being reduced or drawn but, for most purpose of this invention it may be defined as coming within a preferred range of from about three degrees to about fifteen degrees.

The light reduction die 16 may be formed in much the same manner as the heavy reduction die [4. In connection with this die, it will be observed that the outer diameter of the matrix or stock [8 may be a friction fit or, as shown, it may be slightly smaller than the diameter of the annular recess 20 in which it is positioned and, if desired, a pin 56 may be provided to prevent the light reduction die i6 and the matrix 18 from rotating with respect to the die ring 22.

The fact that the dies l4 and I6 are spaced 2. critical distance from one another has already been mentioned. Although this distance will vary according to the dimensions and chemistry of the metal being reduced, the distancebetween the two will generally fall within a preferred range of from one-fourth inch to five inches.

In operation, a metal article, such as a rod or bar, is drawn first through the heavy reduction die, at which stage of the operation, critical stresses (sufllcient to cause cracking) are imparted to the metal and thereafter through the light reduction die to reform the stresses to those having non-critical (non-cracking) values. For purposes of facilitating the description of these operations they may be referred to as impartin to the metal an abnormally heavy reduction followed by a skin-pass."

The practice of taking an abnormal reduction is more fully set forth and described in U. S. Patent No. 2,320,040 granted May 25, 1943, in the name of Landis and assigned to the assignee of the present application.

Having thus described my invention, what I claim as new and desire to secure through Letters Patent of the United States, is:

l. A housing having an opening formed therein with the wall of said opening being of spherical configuration, and a die assembly adapted to fit within said opening to form a ball and socket bearing therewith, said die assembly comprising, in combination, a high reduction die member, a low reduction die member, and means for aligning said die members with respect to one another, said means including a plurality of adjusting members carried by one of said die members and engaging the other' of said die members to effect relative movement of said die members in said socket.

2. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of die-rings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a die carried by each of said rings, axially adjustablemeans carried by said block and engaging a first one of said rings adjacent the periphery thereof to adjust and fix said first ring in said socket, and other axially adjustable means cooperatively engaging said first ring and a second one of said rings adjacent the periphery thereof to adjust and fix said second ring in said socket relative to said first ring.

3. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of die-rings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a die carried by each of said rings, axially adjustable means carried by said block and engaging a rear surface of one of said rings at circumferentially spaced points adjacent the periphery thereof for clamping said one ring against said wall in adjusted position in said socket, and other axially adjustable means carried by said one ring and accessible from the rear thereof, said last mentioned means engaging a rear surface of a second of said rings at circumferentially spaced points adjacent the periphery thereof to clamp said second ring against said wall in adjusted position in said socket relative to said first ring.

4. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of die-rings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a die carried by each ofsaid rings, clamping means threadedly engaging said block at circumferentially spaced points adjacent the periphery of said socket for axial adjustment relative thereto and abuttingly engaging a rear surface of one of said rings to clamp said one ring in adjusted position in said socket, and other clamping means threadedly engaging said one ring and accessible from the rear thereof, said last mentioned means being axially adjustable and extending forwardly from said one ring to abuttingly engage a rear surface of a second of said rings to clamp said second ring in said socket in adjusted relation to said one ring.

5. In a die assembly including a die block having a socket comprisin a wall of spherical confifiiration, the combination of a plurality of dierings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction entrant die mounted in a first one of said die rings, axially adjustable means carried by said block and engaging said first ring adjacent the periphery thereof to fix said first ring in said socket with said heavy reduction entrant die in axially aligned relation, an exit die mounted in a second one of said die rings, and axially adjustable means cooperatively engaging said first ring and said second ring for adjusting said second ring in said socket to align said exit die relative to said entrant die.

I 6. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of dierings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction die mounted in a first one of said die rings, clamping means cooperatively engaging said block and said first ring to adjust said ring on said spherical wall thereby to align said heavy reduction die relative to said socket, a second die mounted in a second one of said die rings, and adjusting members threadedly engaging said first ring and accessible from the rear thereof, said adjusting members extending forwardly from said first ring and abuttingly engaging said second ring to clamp said second ring in said socket with said second die in adjusted alignment relative to sai heavy reduction die.

'7. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of dierings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction die mounted in a first one of said die rings, clamping means cooperatively engaging said block and said first ring to adjust said ring on said spherical wall thereby to align said heavy reduction die relative to said socket, work-engaging straightening means mounted in a second one of said die rings, and axially adjustable members extending through said first'ring and accessible from the rear thereof, said adjustable members cooperatively engagin said rings to effect adjustment of said second ring in said socket relative to said first ring, whereby said straightening means is adjustable relative to said reduction die to insure straight drawing therethrough.

8. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of dierings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction die mounted in a first one of said die rings, clamping means cooperatively engaging said block and said first ring to adjust said rin on said spherical wall thereby to align said heavy reduction die relative to said socket, a straightening die mounted in a second one of said rings and having a cylindrical bore of substantially the size of the work drawn through said reduction die, and axially adjustable members extending through said first ring and accessible from the rear thereof cooperatively engaging said rings to effect adjustment of said second ring in said socket relative to said first ring, whereby said straightening die is adjustable to insure straight drawing through said reduction die.

9. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of dierings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction entrant die mounted in a first one of said die rings, axially adjustable means carried by said. block and engaging said first ring adjacent the periphery thereof to fix said first ring in said socket with said heavy reduction entrant die in axially aligned relation, 9. low reduction exit die mounted in a second one of said rings, and axially adjustable means cooperatively engaging said rings for adjusting said second ring in said socket to effect alignment of said dies.

10. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of a plurality of die-rings having spherically formed surfaces engaging said wall to position said rings in said socket in axially spaced relation, a heavy reduction entrant die mounted in a first one of said die rings, axially adjustable means carried by said block and engaging said first ring adjacent the periphery thereof to fix said first ring in said socket with said heavy reduction entrant die in axially aligned relation, a low reduction die, a straightening die, means mounting said low reduction die and said straightening die in a second one of said die rings in spaced axial relation, and axially adjustable members cooperatively engaging said first and second rings for adjusting the angular relation of said second ring to said first ring in said socket thereby to align said low reduction die and said straightening die with said heavy reduction die.

11. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of die-supporting means in said socket having a spherically formed surface engaging said spherical wall, adjustable means for clamping said die-supporting means in adjusted positions in said socket, a reduction die carried by said die-supporting means adjacent the entrance end of said die block, and straightening means independent of said reduction die carried by said die-supporting means forwardly of said reduction die for receiving and guiding the work during passage thereof from the exit side of said reduction die to the exit end of said die block.

4 12. In a die assembly including a die block having a socket comprising a wall of spherical configuration, the combination of die-supporting means in said socket having a spherically formed surface engaging said spherical wall, adjustable means for clamping said die-supporting means in adjusted positions in said socket, a reduction die carried by said die-supporting means adjacent the entrance end of said die block, and a cylindrical guide me separate from said reduction die and carried by said die-supporting means forwardly of said reduction die for receiving and guiding the work during passage thereof from the exit side of said reduction die to the exit end of said die block.

13. In a die assembly including a die block having a socket comprising a wall of spherical configuration, a die ring having a spherically formed surface engaging said spherical wall, said die ring having an axially extending die receiving opening therethrough, adjustable means engaging a rear surface of said ring and accessible from the rear of said die block for positioning said die ring in said socket, a guide member insertable into said opening from the rear of said die ring, and reduction die means insertable into said aperture behind said guide member to engage a rear surface of said guide member, whereby said guide member is positioned forwardly of said reduction die for receiving and guiding the work during passage thereof from the exit side of said reduction die to the front or exit side of said die ring.

THEODORE s. SEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 401,208 Rapp Apr. 9, 1889 686,365 Thackray Nov. 12, 1901 1,928,227 McCulloch Sept. 26, 1933 2,203,751 Simons June 11, 1940 2,349,652 Fenner May 23, 1944 

